Gene expression studies have led to the identification of different molecular subtypes of invasive breast cancer, including the basal-like triple negative (ER−/PR−/HER2−), HER2 overexpressing, and luminal A (ER+ and/or PR+/HER2−) and luminal B (ER+ and/or PR+/HER2+) subtypes [43, 44]. The gene discussed is ERBB2; the disease is breast cancer.